The brewing of coffee using only coffee beans and water is an art practiced through the world. While many different coffee beans, roasting and grinding techniques, bean/water ratios may be used based on regional and cultural preferences, the basic hot extraction method remains similar. Therein, the bean in desired form is exposed at an elevated temperature for a period of time sufficient to extract the desired constituents for the taste of the end consumer. Against such background, it is widely accepted that excessive brewing temperature can adversely affect the palatability of the resulting brew. Similarly, insufficient brewing temperature results in insufficient extraction and an undesirably weak brew. Further, it is widely accepted that reheating a properly brewed coffee to excessive temperatures can also adversely affect the desired taste. Accordingly, notwithstanding advances in automatic equipment available to the consumer, brewing a highly palatable coffee remains an elusive challenge.
Recently, in addition to regularly brewed coffee, specialized coffee drinks have become popular. Mocha, espresso, cafe latte, cappuccino and the like require brewing techniques not readily and reliably practiced in the consumer setting, and accordingly are available primarily only at commercial settings having specialized equipment and personnel for such products. Also, cold coffees are becoming popular and require a non-bitter coffee concentrate that will maintain desired flavor in the presence of dilution with ice and additives.
In an effort to provide the consumer and the commercial establishment with a wide variety of hot and cold coffee based beverages that can be reliably and repetitively served without specialized equipment, an effort has been made to provide coffee concentrates that can be heated, diluted, cooled, processed and formulated for such applications. However, the basic constituents of coffee have prevented acceptably shelf-stable products from being successfully developed. Coffees, unlike many food and beverage concentrates, deteriorate in unacceptable ways due to enzymatic and bacterial degradation. While such reactions can be retarded through refrigeration, such storage is expensive and effective for limited time periods and compromised unless completely utilized at first consumption, inasmuch as the temperature transients in handling outside the refrigerated setting can accelerate and resume the undesired reactions. Such limitations also reduce the availability and increase the cost of such products to the consumer inasmuch as refrigerated shelf space is expensive in storage or retail facilities. Further, conventional processing and packing techniques have not provided a satisfactory solution. Coffee is an exceedingly complex liquid of aromatics, oils and other flavor and texture enhancing entities contributing to the recognized taste criteria of acidity, body, aroma, flavor and essence. These qualities by presence or absence determine quality and acceptability of the brewed coffee to the consumer.
Consumers demand convenience and quality in newly introduced coffee innovations. There are a number of schemes for providing devices for making a single beverage server, such as a cup of coffee or tea. In one approach a disposable container fits on top of a cup and has a compartment for receiving a beverage extract such as coffee with a large reservoir on top into which a person must pour boiling water. U.S. Pat. No. 5,325,765 describes a beverage filter cartridge that includes an impermeable pierceable base having a predetermined shape and an opening at one end; a self-supporting wettable filter element disposed in the base sealingly engages with the opening in the base and has a form different and smaller than the predetermined shape of the base so that the filter element diverges from the base and divides the base into two sealed chambers, a first chamber for storing an extract of the beverage to be made, and a second empty chamber for accessing the beverage after the beverage outflow from the filter has been made by combining a liquid with the extract; and an impermeable pierceable cover sealingly engaged with the opening in the base to form an impermeable cartridge. That disposable container proved to be very popular due to delivering a quality cup of coffee in a convenient manner. However, the cost of the disposable container is high preventing many frugal consumers from using this technology.
One of the innovated approaches in the liquid coffee industry is to freeze the coffee concentrates during or prior to shipping and storage. When needed, the frozen liquid coffee concentrates are left at room temperature for a few days or as needed to thaw out and then should be used within two weeks otherwise deterioration in quality is noticed. Such an approach is expensive and requires freezing capability prior to and during shipping and handling. It also reduces the duration during which the concentrate is suitable for consumption and unused portions often have to be discarded.
Aseptic thermal processing of coffee concentrates is one of the approaches used to stabilize coffee concentrates. U.S. Pat. No. 6,399,136 describes a shelf stable coffee concentrate for extended periods at ambient temperatures includes an aseptically packaged coffee concentrate. Thermal processing of liquid coffee concentrates reduce desirable coffee aroma and develop off notes in the finished beverage drink.
U.S. Pat. No. 6,054,162 is directed to a liquid coffee in which the development of acidity has been inhibited and which results in a longer shelf-stable product. The method used in making the liquid coffee product of the present invention includes treating the coffee extract with an alkali, the alkali being present in an amount effective to convert acid precursors present in the coffee extract to their respective acid salts, and thereafter neutralizing the treated coffee extract with an acid, the acid being present in an amount effective to neutralize any excess alkali from the first step and to adjust the final pH of the liquid coffee product to the desired value.
Factors that determine the quality of liquid coffee and liquid coffee concentrates may be its acidity and/or level of sulfur containing compounds. The effect acids, acidity, and sulfur levels have on the organoleptic characteristics of a cup of coffee can, in many cases, be determining factors in the consumer appeal of a coffee beverage. For example, too much acidity in a coffee can result in an undesirable sourness to the beverage, while too little acidity in the coffee may cause a flat flavor profile. Maintaining a stable acidity and flavor profile of a coffee beverage can, therefore, be important in producing and maintaining a coffee beverage that is desired by consumers unless new methods are developed to mask the impact of various acidity levels on organoleptic characteristics.
The task of maintaining the optimal acidity of a coffee beverage is not easy because it is believed that over 25 different acids exist naturally in roasted coffee and that many different factors can affect the final acidity of coffee. For instance, coffee may include chlorogenic, malic, citric, acetic, formic, glycolic, lactic and pyroglutamic acids as well as others. In addition, different bean varieties may also affect beverage acidity. For example, the pH of a coffee brewed from Arabica varieties generally has a pH between about 4.85 and about 5.15. Coffee brewed with Robusta beans, on the other hand, generally has a higher pH in the range of about 5.25 to about 5.40. Other processing factors can also affect the degree of acidity, such as, the degree of roast, the roast profile, the nature of the processing and the age of the green beans and the like.
Due to the length of commercial supply chains and the desired shelf life of liquid coffee, a shortcoming exists with liquid coffee concentrates. Liquid coffee concentrates and extracts tend to be an unstable system, and both shelf- and refrigerator-stored liquid coffee products tend to naturally develop an increased acidity and varying flavor profile over a period of time generally due to naturally occurring acid-generating reactions in the beverage. Over time, these acid-generating reactions can slowly change the beverage's pH throughout a product's shelf file so that the beverage's acidity may also slowly change from the day it is produced to later in its shelf life. A rise in acidity or sourness of the beverage (lowering of pH) may translate into an inconsistent product and a loss of quality unless innovative methods are created to mask the impact of acid on taste.
The coffee concentrate manufactures attempt to control acid development in their concentrates and to prevent pH drift down to pH lower than approximately 4.7 to 5.5. One attempted solution to prevent the sourness development in liquid coffee beverages over time is the addition of sodium bicarbonate to elevate the initial pH of the product. However, the pH of the sodium bicarbonate-treated liquid coffee product still falls over time as the naturally occurring acid generating reactions occur, which still results in a varying acidity profile throughout the product's shelf life. U.S. Pat. No. 6,054,162 describes another attempted solution to address the problem of liquid coffee sourness development. The '162 patent describes a method that inhibits the development of acidity by treating a coffee extract with an excessively large amount of alkali relative to the coffee solids to drive a reaction that converts any acid precursors in the beverage to their respective salts to inhibit the generation of acid. However, such method undesirably increases the pH of the coffee to unacceptably high levels with the excessive amounts of alkali (which is needed to drive the desired reactions) and, therefore, also requires neutralization of the treated coffee with an acid to neutralize the excess alkali into respective salts in order to adjust the final pH to the desired value.
US patent application publication no. US 2010/0316784 A1 describes a method for stabilizing liquid coffee concentrates is by blending a liquid coffee concentrate base with an edible alkali source in an amount effective to artificially increase a pH of the liquid coffee concentrate base between about 0.5 to about 1.5 pH units to form a pH increased coffee concentrate. Next, an aromatic and/or coffee flavor is optionally added to the pH increased coffee concentrate. The pH increased coffee concentrate, with or without the flavor additive, is then aseptically processed and thermally treated at about 285 to about 295° F. for about 60 to about 180 seconds to artificially drive acid generating reactions in the concentrate to completion to form a stabilized liquid coffee concentrate.
In general, the processors of liquid coffee concentrates exert every effort to assure the pH of the concentrate remains higher than 4.6 and even if the pH is dropped to below 4.6, it is usually brought up before consumption to pH higher than 4.6, otherwise undesirable sour notes are detected in hot coffee beverages. For instance, U.S. Pat. No. 6,406,730 relates to a process and apparatus for producing low acid food products by which a naturally low acid food product can be acidified for storage and later de-acidified at the point of dispensing for consumption or freezing in suitable equipment.
The phrase “acidified foods” means low-acid foods to which acid(s) or acid food(s) are added and which have a water activity greater than 0.85 and have a finished equilibrium pH of 4.6 or below. Acidified food may be thermally processed, or processed with permitted preservatives to destroy vegetative cells of microorganisms of public health significance and to inhibit the reproduction of microorganisms of non-health significance.
The Code of Federal Regulations (“CFR”) governs many, if not most, aspects of food processing. Specifically, the CFR sets forth distinctions between “low-acid” foods and so called “acidified” foods. According to 21 CFR §114.3, the phrase “low-acid foods” means any foods, other than alcoholic beverages, with a finished equilibrium pH greater than 4.6 and a water activity greater than 0.85. Low acid foods include milk, ice cream, creamers, and milk and/or vegetable fat containing beverages such as flavored cappuccino beverages. Special processing, packaging and handling of these products are necessary to prevent premature spoilage and the growth of microorganisms of public health significance. Current processing standards for unrefrigerated low acid foods require the application of a “minimum thermal process” with the application of heat to food, either before or after sealing in a hermetically sealed container, for a period of time and at a temperature scientifically determined to be adequate to ensure destruction of microorganisms of public health significance.
In the world of coffee, it is generally found that pleasing flavor and aroma are particularly desirable characteristics in coffee products. Such characteristics are commonly associated with freshly brewed, high quality coffee. If a coffee product lacks a pleasing flavor and aroma, it is often perceived by the consumer to be of lesser quality. Soluble, or instant, coffee has unfortunately developed a reputation in the coffee industry, and among some consumers, as being a less desirable choice in coffee beverages because it lacks the flavor and aroma of high quality, freshly brewed coffee.
Thus, for many years, producers of soluble coffee have sought to reduce or eliminate the perceived differences between soluble coffee and freshly brewed coffee. Not surprisingly, the majority of this effort has focused on flavor and aroma improvement. Soluble coffee is commonly prepared by spray drying or freeze drying a hot water extract of a roasted coffee. This preparation process often results in a soluble coffee product which is lacking in some of the desired flavors and aromas typically associated with high quality, freshly brewed coffees. Alternately, the soluble coffee may have additional flavors and aromas considered undesirable, such as “instant” flavors or aromas. Unfortunately, this often results in the aforementioned negative perception of soluble coffee by consumers.
Many attempts to remedy this problem have been made, the most common being the incorporation of oils containing aroma constituents into the soluble coffee. The process of adding aromas to soluble coffee is known as aromatization. Aromatization generally involves capturing an aroma in a substrate, such as an oil or emulsion. See, for example, U.S. Pat. No. 5,222,364. Usually coffee oil or an emulsion of coffee oil and coffee extract is used as the substrate. The aroma-containing substrate may then be sprayed on, or injected into, the soluble coffee powder prior to the coffee being packaged in containers and sealed. The theory of aromatization is that adding aromas to soluble coffee via oils provides a soluble product which more closely mimics the aroma of fresh roast and ground coffee.
While aromatization is effective for improving the aroma of soluble coffee to some extent, it is not without its difficulties. With the substrates generally used to carry out aromatization, it is often found that either the incorporation of the aroma and/or substrate is too good, or not good enough. If the incorporation of the aroma is too good, the aroma is effectively trapped within the substrate and not sufficiently released. Thus, the consumer is unable to experience the benefit of improved aroma in the soluble coffee product when it is prepared. In an attempt to remedy this problem, recent developments suggest that aroma-enriched microemulsions of coffee oil may be used to improve the aroma of soluble coffee. See U.S. Pat. No. 5,576,044. Such microemulsions add aroma to the soluble coffee without the use of surfactants and stabilizers. However, the process of collecting the aromas and then adding them to the soluble coffee is costly when compared to manufacturing conventional soluble coffee without added aroma oils. This increased cost in the manufacturing process must then be absorbed by the consumer at the point of purchase.                Additionally, the addition of aroma oils does nothing to remedy the deficient perceived flavor of the soluble coffee. It merely improves the perception of aroma when a new container of instant coffee is first opened. On the other hand, if the incorporation of the aroma is not good enough, the aromas will volatilize before, or soon after, incorporation into the product and again, the desired benefit will be lost. Additionally, if the incorporation of the aroma-enriched oil into the soluble coffee is not good enough, and the oils are not properly blended with the soluble coffee, there is a tendency for an unpleasant oil slick to form on the top of the product.        
Thusly, a well established need continues to exist for a packaged concentrated coffee product having extended storage life at ambient temperatures that retains full flavor without diminution over time and may be added to hot or cold water to produce various coffee formats.